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WiFi device management

Let's setup a WiFi network that can be used to connect to our Raspberry PI so we can manage it.

  1. First of all, install hostapd
apt install hostapd -y

Raspberry's pi builtin wireless card allows virtual devices. You can check it with:

iw list

...
    Supported interface modes:
         * IBSS
         * managed
         * AP
         * monitor
         * P2P-client
         * P2P-GO
         * P2P-device
...
    valid interface combinations:
         * #{ managed } <= 1, #{ monitor } <= 1, #{ P2P-device } <= 1, #{ P2P-client, P2P-GO } <= 1,
           total <= 4, #channels <= 2
         * #{ managed } <= 1, #{ AP } <= 1, #{ monitor } <= 1, #{ P2P-client } <= 1, #{ P2P-device } <= 1,
           total <= 5, #channels <= 1
...
  1. Create the virtual interface and assign an IP address:
iw dev wlan0 interface add uap0 type __ap

ip addr add 192.168.191.1/24 dev uap0

Make the interface not be managed by Network Manager

nmcli dev status
DEVICE         TYPE      STATE                   CONNECTION
wlan0          wifi      connected               <somessid>
uap0           wifi      disconnected            --
p2p-dev-uap0   wifi-p2p  disconnected            --
p2p-dev-wlan0  wifi-p2p  disconnected            --
eth0           ethernet  unmanaged               --
lo             loopback  unmanaged               --

nmcli dev set uap0 managed no

nmcli dev status
DEVICE         TYPE      STATE                   CONNECTION
wlan0          wifi      connected               <somessid>
p2p-dev-wlan0  wifi-p2p  disconnected            --
eth0           ethernet  unmanaged               --
lo             loopback  unmanaged               --
uap0           wifi      unmanaged               --
p2p-dev-uap0   wifi-p2p  unmanaged               --

We'll set the above steps plus random MAC to be executed at every boot.

Create a udev rule at /etc/udev/rules.d/90-wireless.rules

ACTION=="add", SUBSYSTEM=="ieee80211", KERNEL=="phy0", \
    RUN+="/usr/sbin/iw phy %k interface add uap0 type __ap" \
    RUN+="/usr/bin/ip addr add 192.168.191.1/24 dev uap0" \
    RUN+="/usr/bin/macchanger -r uap0"
ACTION=="add", SUBSYSTEM=="net", KERNEL=="uap0", ENV{NM_UNMANAGED}="1"
  1. Set /etc/hostapd/hostapd.conf file as follow:
interface=uap0
driver=nl80211
#. SSID with a empty space would be nice
ssid= 
channel=6
ignore_broadcast_ssid=1

wpa=2
wpa_passphrase=0123456789
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP

hw_mode=g
macaddr_acl=0
auth_algs=1
  1. Enable hostadp service on boot and start it now:
systemctl enable --now hostapd

Wrap up​

The above setup should create a hidden WiFi network:

  • SSID: " " # Yes, just a literal empty space.
  • Password: 0123456789
  • Channel: 6
  • MAC: random
  • IP: 192.168.191.1
  • Subnet: 192.168.191.1/24

REFs​